Millisecond-Level Minority Carrier Lifetime in Femtosecond Laser-Textured Black Silicon

Xiaolong Liu*, Behrad Radfar, Kexun Chen, Elmeri Pälikkö, Toni Pasanen, Ville Vähänissi, Hele Savin

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)
57 Downloads (Pure)


Femtosecond laser-textured black silicon (fs-bSi) is known to suffer from heavy minority carrier recombination resulted from laser irradiation. In this paper, we demonstrate that the thermal annealing step, generally used to recover the crystal damage, could improve the minority carrier lifetime of the fs-bSi wafers only from 8 μs to 12 μs, even when using as high temperature as 800 °C. However, with an optimized wet chemical etching process, we obtain a high minority carrier lifetime of 2 ms without sacrificing the optical properties of the samples, i.e., the absorptance remains above 90% in the studied wavelength range (250–1100 nm). Increasing the etching time further leads to a total recovery of the lifetime up to 10.5 ms, which proves that the damage originating from the fs-laser texturing extends only to the near-surface layer (a few μm) of silicon.
Original languageEnglish
Pages (from-to)870-873
Number of pages4
JournalIEEE Photonics Technology Letters
Issue number16
Publication statusPublished - 15 Aug 2022
MoE publication typeA1 Journal article-refereed


  • annealing
  • black silicon
  • charge carrier lifetime
  • etch back
  • fs-laser
  • recombination
  • silicon


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